Common peripheral input devices of a computer include a mouse, a keyboard device, a trackball device, and the like. The keyboard can be used by users to directly input words and symbols to the computer and is therefore draw attention from users and input device manufacturers. A keyboard including a scissor-type connecting element is pretty common.
Referring to FIG. 1, FIG. 1 is a schematic structural diagram of a conventional notebook computer. The conventional notebook computer 1 includes a base 10, an upper cover 11, a rotation shaft 12, and a keyboard 13. Moreover, a screen 111 is disposed on the upper cover 11, and the upper cover 11 may cover the base 10 or may be raised to be in a use state by means of rotation of the rotation shaft 12. The keyboard 13 is disposed on the base 10 and is capable of being operated by a user to generate a corresponding key signal. That is, the keyboard 13 is in a state in which the computer is used.
The structure of the keyboard 13 is subsequently described. One key in the keyboard 13 is used as an example for describing the structure of the keyboard 13. Referring to FIG. 2, FIG. 2 is a schematic cross-sectional structural diagram of a part of a conventional keyboard. The keyboard 13 includes key caps 131, scissor-type connecting elements 132, elastic rubber bodies 133, a membrane switch circuit 134, and a baseboard 135, and the baseboard 135 is configured to bear the second key caps 131, the scissor-type connecting elements 132, the elastic rubber bodies 133, and the membrane switch circuit 134. The scissor-type connecting elements 132 are configured to connect the baseboard 135 and the key caps 131.
The scissor-type connecting elements 132 are located between the baseboard 135 and the key caps 131 and separately connect the baseboard 135 to the key caps 131, and the elastic rubber bodies 133 are surrounded by the scissor-type connecting elements 132. The membrane switch circuit 134 has a plurality of key connecting points (not shown). The key connecting points output corresponding key signals when being triggered. The elastic rubber bodies 133 are disposed on the membrane switch circuit 134 and one elastic rubber body 133 corresponds to one key connecting point. When an elastic rubber body 133 is triggered, the elastic rubber body 133 deforms and presses a corresponding key connecting point in the membrane switch circuit 134, to generate a key signal.
The operation of a conventional key cap 131 when being pressed by a user is described below. In FIG. 1, when a user presses the key cap 131, the key cap 131 is under a stress and pushes the scissor-type connecting element 132 to move. Therefore, the key cap 131 may move downwards relative to the baseboard 135 and presses a corresponding elastic rubber body 133. At this time, the elastic rubber body 133 deforms and presses the membrane switch circuit 134, to trigger a key connecting point of the membrane switch circuit 134, so that the membrane switch circuit 13 outputs a corresponding key signal. When the user stops pressing the key cap 131, the key cap 131 is no longer under a stress and stops pressing the elastic rubber body 133, so that the elastic rubber body 133 recovers to the original state due to its elasticity and meanwhile provides an upward elastic restoring force, and the key cap 131 is therefore pushed back to the position before being pressed.
In recent years, touch type apparatuses may enable a user to operate directly with fingers or by using a touch pen, have an advantage of easy operation, and therefore are favoured by users and large manufacturers. Therefore, the screen 111 in the notebook computer 1 may use a touch type screen and therefore have a touch function. In another aspect, some manufacturers further launch a notebook computer capable of being bent inversely. Referring to FIG. 3, FIG. 3 is a schematic structural diagram of a conventional notebook computer in a touch mode. The upper cover 11 of the notebook computer 1 shown in FIG. 3 is turned over towards the bottom of the base 10 by means of the rotation shaft 12, so that the upper cover 11 is turned over to a state at which the upper cover 11 is in contact with the bottom of the base 10 and the screen 111 is exposed, that is, in an appearance similar to that of a touch type apparatus. The screen 111 is a touch type screen, and therefore a user may use the notebook computer 1 as a touch type apparatus.
However, it is difficult for a user to hold the notebook computer 1 because the keyboard 13 of the notebook computer 1 in a touch mode is exposed outside and the key cap 131 may move downwards to form a dent since the user may press the key cap 131 with hands when holding the notebook computer 1. In addition, the notebook computer 1 also generates a key signal when the key cap 131 is touched by mistake when the notebook computer 1 is held by the user, so as to generate a false operation, resulting in difficulty in user operation.
Therefore, a keyboard in which the height of a key cap is changeable along with a change in the appearance of a notebook computer is needed.